1 — Pulmonary alveolus; 2 — Respiratory bronchiolus; 3 — Pulmonary artery, branch; 4 — Thoracic aorta, bronchial branch; 5 — Pulmonary
vein, branch
1 — Pulmonary alveolus; 2 — Respiratory bronchiolus; 3 — Pulmonary artery, branch; 4 — Thoracic aorta, bronchial branch; 5 — Pulmonary
vein, branch